What action should a private investigator take if they inadvertently obtain highly sensitive personal information (e.g., medical records) without proper authorization during an investigation?

1. Use the information if it's highly relevant to the case
2. Immediately secure the information, cease its use, and seek legal counsel or guidance from the information commissioner regarding its proper destruction or return.
3. Share it with the client if they promise to keep it confidential
4. Keep it on file for future reference but do not use it